This invention relates to liquid detergent compositions. More specifically, this invention relates to liquid detergent compositions which are particularly suited for use on infant and children's clothing.
Liquid detergent compositions suitable for home laundry use first became available in the late 1950's and early 1960's. Traditionally, the first commercial household cleaning materials were produced in a liquid form for the washing of delicate fabrics, dishes and the hair. When these new materials were directed towards heavy duty washing, e.g. clothing and other fabrics, it was found that formulation constraints led liquid laundry detergents to be inferior in cleaning performance compared with powder or granular form. The key to the performance superiority of granular products was their ability to accommodate high levels of sequesterants (builders) whereas the early liquid products could not contain high levels of both surfactant and builder and still remain as stable one-phase solutions.
Since that time, numerous liquid detergent formulations have been set forth in the literature and many have become commercially available. Most of these formulations are based on anionic-nonionic surfactant mixtures. Many of these mixtures of surfactants are not particularly good cleaning agents and therefore the resulting products are not entirely satisfactory. In particular, they do not provide satisfactory cleaning for infant laundry, e.g. diapers and high cotton content infant wear, over a range of conditions. The fact that these products do not contain builders permits calcium and magnesium ions to inactivate the anionic surfactants in hard water conditions. Furthermore, most liquid detergent formulations are inherently of high viscosity due to their high anionic-nonionic surfactant content and hence require volatile solubilizers such as ethanol or propylene glycol to provide appropriate viscosities and stability to permit consumer use.
An advantage of liquid detergents is that they are far more suitable than granular products for spot-cleaning and hand laundry; being predispersed in water they immediately attack the stain and instantly disperse when further water is added. These products, however, tend to be somewhat irritating for use in hand-laundering, a frequent method for washing certain infant wear. This results from the high surfactant levels and the presence of solvents in these products coupled with the presence of solubilizers.
One commercially available granular product directed to this market is satisfactory in its cotton cleaning capability but, since it is soap-based, it results in the formation of insoluble precipitates of calcium and magnesium thereby depositing on the fabrics what is known as soap "scum" or "curd" which may be irritating to the wearer of such fabrics. Further, such soap-based products provide rather poor cleaning of synthetic fabrics. The formation of soap "curd" is also known to inhibit the flame retardancy of the specially-treated fabrics used in infants' sleepwear.
In summary, there is no commercial product presently available which combines cotton cleaning ability competitive to soap products, as well as acceptable cleaning ability on synthetic fabrics, the absence of residue deposition, the convenience of liquids, substantial mildness to those using these products for hand laundering and an inherently low viscosity.
It is an object of this invention to provide a stable liquid detergent composition which has superior cotton cleaning characteristics and which provides acceptable cleaning of other garment fabrics.
It is a further object of this invention to provide an inherently low viscosity liquid detergent composition which totally disperses in water and does not form insoluble, irritating precipitates and which also does not interfere with the flame retardant properties required for infant sleepwear.
It is still a further object of this invention to provide liquid detergent compositions which provide excellent cleansing of infant diapers and infant clothing, yet in comparison with other liquid detergents, is much milder to the skin.
These and other objects are achieved by the compositions of the present invention as hereinafter described.